public class Main {
    public static void main(String[] args) {
//        String url = "https://v.qq.com/iframe/preview.html?width=500&height=375&auto=0&vid=d0926dsfl54";
        String url = "&vid=d0926dsfl54";
//        String url = "vid=d0926dsfl54";
        int index = url.indexOf("vid=");
        String substring = url.substring(index + 4);
        System.out.println(substring);
    }
}
